Self-releasing sprag for one-way clutches



June 2l, 1955 L T. SZADY SELF-RELEASING sPRAG FOR ONE-WAY cLUTcHEs Filed March 2, 1955 INVENTOR. LEO POLD T. SZADY FIGJ.

ATTORNEYS 2,711,238.,` e e SELF-RELEAsmG sPRAG Fon ONE-WAY cLU'rcHEs Leopold T. Szady, Hamtramck, Mich., assig'nor to Formsprag Company, Van Dyke, Mich., a corporation of Michigan K y f' Application Mgr'cnfz, 1953, 'serial No. 339,800

6 claims. (ci. 19a-45.1)

The invention relates to sprags for one-way clutches and of that type comprising opposite eccentric cam faces for respectivelyengaging ou'terl and inner concentric raceways of the clutch. Such sprags, when arranged. between the raceways, must be energized or biased to turn into frictional contact therewith. This` in certain` clutch constructions is formed by one or more radially contractable garter springs surrounding the series of sprags and engaging recesses ,therein with `bearings positioned to rock each sprag on the inner raceway. However, when the clutch is revolving, centrifugal force in each sprag may either counteract or supplement theenergizing means in accordance with the position of the center of gravity with respect to the center of curvature of the outer cam face. For most clutches it is desirable to have a construction of sprag in which centrifugal force is neutralized, neither increasing nor diminishing the energizing force. On the other hand there are certain clutch uses such as in an overrunning mechanism connected to the outer race member where it would be desirable to utilize centrifugal force for withdrawing the sprags from rubbing contact with the inner race member at some predetermined velocity of rotation.

It is the object of the invention to obtain a construction of sprag and method of forming the same by which the eifect of centrifugal force thereon while in working position can be exactly predetermined. It is a further object to obtain this result starting with a sprag blank of a standard form and cross-sectional contour and from which all variations may be easily produced. With these objects in view, the invention consists in the construction and method as hereinafter set forth.

In the drawings:

Fig. 1 is an elevation of a portion of a one-way clutch showing the sprags in relation to the raceways and also the energizing means therefor;

Fig. 2 is a perspective view of a polygonal blank from which the sprag is formed;

Fig. 3 is a perspective view of a sprag having a portion thereof cut away to change the location of the center of mass;

Fig. 4 is a cross-section through the sprag as in Fig. 3 in its relation to the raceways in released position.

One type of sprag which has been used extensively in one-way clutches has a cross-sectional contour which might be generally described as a combination of a rectangle and a triangle. However, the opposite ends of the rectangular portion are actually eccentric curves while the triangular portion projects beyond these curves and has a rounded apex centrally therebetween. One important advantage of such a contour is that the same sprags may be used in clutches having raceways of different radii and consequently differing in the number of sprags forming a complement. Another advantage is that the centers of the curves may be located in any desired relation to the center of mass. Still another advantage is that the sprag blanks may be formed from a drawn rod of a desired contour cut into suitable lengths l` as to be substantially neutral.

Y sectional' andwithout the necessity of surfaces. Forforming my improved sprag the crosscontourfof the drawnl rod 4preferablyv has the center ofthe curved'face for engaging withathe outer raceway 'so locatedwith'rrespect to Vthe center of` mass ing position centrifugal force turn the sprag'one way `o`r the other; Thus for general use in one-way clutches such sprags without 'alteration are` suitable. `If,' however, it-is `desired to' chang the relation between the centers of curvature and theA center of mass, thismay beiacco'mplished by cutting away a portion ofthe triangular projection. This maltesfit possible to form'from the same'stock and the same blanks.'

cut therefrom,I v'sprags having any predetermined moment of inertia for'turning them in 'a' direction counter to that t tendingside A',

produced by the energizingmeans. way clutch may be formed inf'whi velocityl of 'rotation centrifugalforce will withdraw the sprags from kkrubbing contact with the inner race member.

The `specific blank A, preferably cut from a drawn rodas above described, 'has a substantially radially ex- Consequently a one-- side having a rounded nose portion Azfa'ndeccentric' arcuate opposite end portions A3 and A4 having their respective centers at B and B'. The center of gravity of the cross section is 'at point C. Fig. 1 illustrates the position of the sprag in a clutch, the axis of revolution of which is D and having the concentric raceways E and E' which are respectively in contact with the arcuate ends A3 and A4. It will be noted that the center of gravity C lies in a radial line from the axis D to the point of tangency F of the surface A3 with the raceway E.Y Consequently the masses in the sprag on opposite sides of this line counter-balance each other and centrifugal force acting on the sprag will have no tendency to turn it either one way or the other.

For energizing the sprags, a radially contractable garter spring G extends through notches or channels H in the sprags having bearing atthe point I at the left so as to bias the sprag to rotate 'anti-clockwise. This will bring both surfaces A3 and A4 into frictional contactv with their respective raceways E and E taneous clutching when the inner surface E is revolved clockwise.

The construction just described is desirable for many, if not most, uses of the one-way clutch. If, however, it is desired to have a clutch which will automatically release the sprags from rubbing contact at a predetermined velocity of rotation, follows: Y

A portion of the triangular projection terminating in the nose 'portion A2 may be cut away, as indicated at K, which will shift the center of gravity to the left as indicated at C', Fig. 4. This will make the mass to the left of the radial line D-F greater than that to the right of said line and will create a moment of inertia proportional to the length of a line J between the points C and C. It is obvious that by removing a greater or lesser amount ofthe triangular portion, the length of the line J can be varied and the amount of centrifugal force developed at any predetermined velocity of rotation correspondingly changed. It is, therefore, only necessary to develop a centrifugal force which is in excess of the force of the energizing spring G, whereupon the sprag will be rotated clockwise to withdraw it from frictional contact with the inner race member. v The cutting away of a portion asindicated at K will not alter the normal function of the triangular portion of the sprag as there will remain portions K and K2 at opposite ends. These will be suiiicient to form contact with further fashioning'the curved In other words, in work will have little effect 'to' h at a predetermined' a triangular projection at the opposite to elfect instan-y Y this may be accomplished ask Whatr I claim as my invention is:

l. A sprag for one-wayliltchesncornprising 'i-pris-n i' matic body having eccentrielearn faces which are substantiallyidiametriaally fepposite with .repet teaieneir only, being variabel Veut awayi tmseletivelY-:lecate the.,

center-.0f massiwth respect t9, said lram .faees.

2f lThemtllfadl. @f fomiirlig` .Spragsffpr .rma-way clutches with@ Seletiveloation of. .theeeriter Qfmasswith @596g t0, the: working Snrfaee, A.:QmpriSiHg forming ya prmati ASpra .may having-e ntrie faces diametrically opposite Wtkrewmt. to a longitudinal axis of` the, prim and alsqfhaving va body :Partien intermediete Saki far@ projecting tranevemely @remate-r .dietanse from aid axis than the yPartien. 9i `sai vbody.t1ia1-1etr- Cally .oppoite the same .andfvariablyleutting away Said projecting poum only to $hift the center af, mass teme desiresloeation with respect t0 .Said @am faces.

3 The ntrution ris-in` claim .1 rl Whih the out away portion extends only apart of thelength of, said primarie bodyY Y f 4.. VThe Construeton .aa in slairn l inswhich the cut. awayponiop is,` between unaltered ,opposite end portions.

of said prisrriatic body,

outer arcuate end face so Aas to'^`oppose`the energizing force by centrifugal forgetg@ dgggggwhich will withv draw the sprags from rubbing contact with the inner race member at a predetermined velocity of rotation. zov [Referene Cited in the1bf1hispatent UNITED vrSFATES lAIlgINTS if 1,952,461 y Roos f Mar-.27, 1934 2.381799 -Dodge 1945 *2,486,252* Davis K E V Oct. 25, v1949 Y Q j, EQREIGNPATENTS A 637,610 -France a e e e; Feb. 6, "119281 cutaway to locate the center of mss'vin relation to the center of the arcuate face which forms the radially outer end of the sprag when in working position in the clutch.

6. In a one-way clutch of the type including spaced coaxial raceways respetively l :gn relatively rotatable members,ra series of VspragS between said Vravyalys and a radiallyeoiitaetalslegggY sprags; each sprag beirgforre having eceentriqaregate; opppit the lr-etpeetire raewayaandan A one side thereof variablymgtgaway to selectively locate the center of mas .with respegtdtowtbe center of the from a prismatic blank nl! fears .f Qf: engaging faces are eccentric arcs and said projecting portionis @Springeforwenergiziag said I entfienreieetienffrom 

